Late deciders aid Clinton

In the battle for Democratic nominee, the issue of negative campaigning is likely to play a role and influence the outcomes.A higher-than-usual number of voters decided on who to support in Ohio and Texas in the last few days before Tuesday's primaries. And they swung, in large measure, to Hillary Clinton.

Exit polls done for ABCNews show the New York senator won those who made up their minds in the last few days by 20 points in Ohio and 23 in Texas.

It was a period when Illinois Senator Barack Obama was dealing with questions about his NAFTA policy, and the trial of a former political fundraiser with ties to the senator got started in Chicago Monday.

And a Clinton ad questioning who'd best manage national security in the middle of the night emerged. If this was a negative ad, one Clinton supporter in Chicago isn't shying away from it:

"Everything has been thrown at Hillary Clinton, including the kitchen sink all during this campaign, so if she is fighting back then that is what she needs to do," said Delmarie Cobb, Clinton supporter.

Cobb just returned from Texas. She saw late negative ads work when she was Jesse Jackson's travelling press secretary during his 1988 White House run.

"That's what you do in campaigns. What, you are not supposed to say that? That is why there is a double standard in this campaign. It is as if he can throw a rock and hide his hand, and if she goes up to him and hits him back, then she's the bully," said Cobb.

"He had a very bad week, and he had a bad last three to five days, and she had a good one," said Don Rose, political consultant.

This longtime political consultant and Obama supporter says late deciders typically go to the perceived incumbent -- who Tuesday night was Obama -- due to his lead in the delegate count.

"She was leading by 20 points three weeks ago, so in one way you could say this is a significant diminution for her, but we are playing it as a stopping of Obama because Obama is in the incumbent position right now," Rose said.

Rose said Clinton is vulnerable on questions about her income taxes and her role on Wal-Mart's board when the company was engaging in anti-labor union practices.